title: FIBTEM PLUS provides an improved thromboelastometry test for measurement of fibrin-based clot quality in cardiac surgery patients.
abstract: BACKGROUND
  The viscoelastic functional fibrinogen (FF) and FIBTEM assays measure the contribution of fibrin to clot strength. Inhibition of platelet function is a necessary precondition for these tests to work. We investigated a novel test for measuring fibrin-based clotting, FIBTEM PLUS, in cardiac surgery and compared it with FF and FIBTEM.
  
  
  METHODS
  A prospective, observational study was performed which included 30 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Blood samples were drawn at the beginning of surgery (pre-CPB), approximately 20 minutes before weaning from CPB and 5 minutes after heparin neutralization. FF, FIBTEM, and FIBTEM PLUS tests were performed in duplicate for all blood samples. Additional coagulation parameters, including platelet count, plasma fibrinogen levels, factor XIII activity, and heparin concentration, were also recorded for each sample.
  
  
  RESULTS
  At all time points, the lowest mean maximum clot firmness (MCF) was observed with FIBTEM PLUS, although a statistically significant difference between FIBTEM and FIBTEM PLUS was observed only at baseline (mean values 22 vs 19 mm, P = 0.01; FF value for comparison: 27.7 mm). FF maximum amplitude (MA) values were significantly higher than FIBTEM MCF and FIBTEM PLUS MCF pre-CPB, during CPB and after heparin neutralization (P ≤ 0.001 for FF MA versus FIBTEM MCF and for FF MA versus FIBTEM PLUS MCF at all time points). The difference between FIBTEM MCF and FIBTEM PLUS MCF correlated with platelet count (r = 0.46;P < 0.001), whereas differences between FF MA and FIBTEM MCF, or FF MA and FIBTEM PLUS MCF did not (r = -0.07, P = 0.51; r = 0.16, P = 0.12, respectively). Differences between the assays were unrelated to heparin levels, which decreased considerably after protamine administration compared with heparin levels recorded before weaning from CPB (decrease from 2.1 to 0.1 U/mL and from 2.8 to 0.2 U/mL for anti-factor IIa and anti-factor Xa, respectively). Agreement between duplicate measurements was similar with FIBTEM and FIBTEM PLUS assays and lower with FF. Significant positive correlations were found between MCF or MA and fibrinogen concentration (all P < 0.001); the highest correlation was with FIBTEM PLUS MCF (r = 0.70).
  
  
  CONCLUSIONS
  The FIBTEM PLUS assay produces precise results. At baseline, it provides greater inhibition of platelets than FIBTEM, but there is no meaningful difference between FIBTEM PLUS and FIBTEM in patients with low platelet counts.
authors.affiliation: From the *Department of Anesthesiology and Intensive Care, Salzburger Landeskliniken SALK, Salzburg, Austria; †CSL Behring, Marburg, Germany; ‡Department of Cardiothoracic and Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy; §Haemostasis Research, Ludwig Boltzmann Institute for Experimental and Clinical Traumatology and AUVA Research Centre, Vienna, Austria; ‖Department of Anesthesiology and Intensive Care, AUVA Trauma Hospital of Salzburg, Salzburg, Austria; and ¶Laboratory Medicine, Unilabs Coagulation Laboratory, Zurich, Switzerland.
authors.forename: Cristina
authors.initials: C
authors.lastname: Solomon
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Baryshnikova
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Schlimp
authors.forename: Herbert
authors.initials: H
authors.lastname: Schöchl
authors.forename: Lars M
authors.initials: LM
authors.lastname: Asmis
authors.forename: Marco
authors.initials: M
authors.lastname: Ranucci
mesh_terms: D000368:Aged; D001777:Blood Coagulation; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000502:physiology; D006348:Cardiac Surgical Procedures / Q000295:instrumentation* / Q000379:methods; D001026:Coronary Artery Bypass / Q000295:instrumentation / Q000379:methods; D004548:Elasticity; D005260:Female; D005337:Fibrin / Q000032:analysis* / Q000737:chemistry*; D005340:Fibrinogen / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013916:Thrombelastography / Q000379:methods*; D014783:Viscosity
chemical_list: D005337:Fibrin; D005340:Fibrinogen